Pressure adjustment means for bolted contact switch



JNVENTOR.

ATTORNEYS July 29, 1969 U UL 1 3,458,680

PRESSURE ADJUSTMENT MEANS FOR BOLTED CONTACT SWITCH Filed Jan. 2, 1968 EDWIN E. KUSSMAUL E 02 V F Q N n 0 ET M H H (v 9 9 XKE r v mm m J 1 n" U m LI H 1 11; mm 3 mw mm $.11 h vm mm L v m fi W 3 n F @Q ow United States Patent 3,458,680 PRESSURE ADJUSTMENT MEANS FOR BOLTED CONTACT SWITCH Edwin E. Kussmaul, Westwood, Mass., assignor to The Kelek Company, Norwood, Mass., a corporation of Connecticut 7,

Filed Jan. 2, 1968, Ser. No. 694,616 Int. Cl. H01h 1/50 US. Cl. 200170 4 Claims ABSTRACT OF THE DISCLOSURE Contact pressure on the blade of a bolted contact switch is adjusted by mounting a locking pin in one of a plurality of clearance hole positions in a pressure plate. A pivotal pressure bolt is threaded in the pressure plate and passes through a clearance hole in the blade. The pressure plate is prevented from rotating with respect to the blade by the locking pin which projects into a second clearance hole in the blade.

BACKGROUND OF THE INVENTION The field of this invention generally comprises manual and power operated knife switches characterized by the provision of bolt means to apply pressure to the blades at one or both ends thereof when the switch is in the closed position. These are sometimes called bolted contact switches. The purpose of such pressure is to reduce contact resistance and to resist electro-magnetic forces generated by relatively high currents, which forces may produce unintended opening of the switch. In the switches pertinent to this invention, the pressure bolting means are commonly automatically operated by the blade pivoting means when the switch is in closed position.

United States Patent No. 2,960,590, dated Nov. 15, 1960, to applicant and Charles E. Burt, discloses a bolted contact switch with pressure bolting means in which tension is applied to a bolt by relative rotation of two members threaded together, which members are coaxial with the bolt. One of the members is a pressure plate or hub having a set screw to prevent the member from rotating in relation to the blade. The other member is rotated by a collapsible triangle linkage. The blade and jamb are thus forced together.

In this and similar devices, it is desired to be able to adjust the contact pressure and this is accomplished by providing a number of holes so as to permit the pressure plate to be secured to the blade in any one of several angular positions. Commonly, the adjustable pressure plate has a number of holes in it and the blade has one or only a few holes. The holes in the pressure plate may be threaded in which case the hole or holes in the blade are clearance holes for the set screw, or the holes in the pressure plate are clearance holes, in which case the hole or holes in the blade are threaded. In either case, the number of threads is necessarily limited by the thickness of the threaded member. In some cases this might be disadvantageous, for if the threads are worn down or broken the set screw might fall out and permit the pres sure plate to move in relation to the blade.

Another disadvantage is the necessity of tightening the set screw by gaining lateral access to the plane in which the blade rotates. This is difficult to do when the switch is mounted in a small or poorly illuminated location.

SUMMARY OF THE INVENTION The features of this invention, which are adapted to a number of different structural embodiments, include the use of a double-flanged pressure plate in conjunction with a locking pin that can be held in any desired adjustment 3,4'58,680 Patented July 29, 1969 hole position by means of a cotter hair pin or the like. There is no reliance on a threaded connection. Also, no lateral access for changing the pressure adjustment is required, and therefore it is easier to make the adjustments.

BRIEF DESCRIPTION OF THE DRAWING DESCRIPTION OF THE PREFERRED EMBODIMENT The invention is described as applied to a bolted contact switch of the type described in applicants copending US. application Ser. No. 612,592, filed J an. 30, 1967.

The switch is assembled on one side of an insulating base 12 formed of a reinforced phenolic, or cast in some other suitable material such as another plastic. The base preferably has an elongated central recessed undersurface of sufiicient depth to include the heads of eight screws 16, permitting a clearance between these screws and the surface of the housing in which the switch may be mounted, for example a sheet metal switch box.

Secured to the base by the screws 16 area pair or cam terminals 18a and 18b and a pair of jarnb terminals 20a and 20b. These terminals are all formed of sheet metal, preferably copper, and have sufficient thickness and cross section to carry the current for which the switch is designed. Suitable means such as ears 22 are provided for the attachment of other circuit parts such as husses or fuses. Metal spacers 24 receive screws 26 threaded in the pairs of terminals to hold them in spaced relationship, with the two pairs of terminals being in mutual alignment as shown in FIG. 1. The terminals have mounting flanges 28 for receiving the screws 16.

The terminals 181: and 18b have identical cam surfaces 30 and 32 and the terminals 20a and 20b have identical aligned slots 34 that function as a part of the operating and locking mechanism described below.

The switch has two identical pivotal blades 36 formed of sheet metal, preferably copper, of rectangular shape With curved corners 38 for clearance at their pivotal ends. The blades are mounted with the spaced parallel portions of the terminals between them.

The means for mounting the blades 36 upon the terminals also form parts of the switch operating and pressure applying mechanism. These means include an operating handle 40 which serves as a link in a collapsible triangle linkage, and a yoke 42 with bifurcated cam follower portions 44 between which a pivot pin 46 is secured, the pin passing through an elongated slot 48 in the operating handle 40. The operating handle preferably has a flat portion 50 for attachment of manual or power operating means of any desired type.

A bolt 52 with its ends respectively threaded in opposite senses is secured to the operating handle 40 by welding or other suitable means. A bolt 54 with its ends also threaded in opposite senses is similarly welded or otherwise secured to the yoke 42. The bolts 52 and 54 pass freely through holes in the ends of the blades 36, and the bolt 52 also passes freely through holes in the terminals 18a and 18b. Thus the blades are pivotal about the bolt 52, while the bolt 54 is in a position to be moved into or out of the slots 34 in the terminals 20a and 20b.

Pressure plates 56 are threaded on the end of the bolts 52 and 54, the plates having peripheral grooves 57 defining flanges and also having a plurality of holes such as 58 which are clearance holes used selectively to receive locking pins 59 which project into clearance holes 60 in the blades 36. Each locking pin has a central lateral hole 61 as shown in FIG. 3, which receives a cotter hair pin 62, the latter fitting substantially within the groove 57 as shown in FIG. 4. The groove 57 is sufiiciently deep to clear the holes 58, as shown. Once so adjusted, the pressure plates 56 remain fixed in relation to the blades.

The threads of the bolts are so directed that the pair of pressure plates on each bolt are closer together, when the operating handle and yoke are aligned with the blades 36 as in the fully closed position of FIG. 2, than they are when the handle and yoke are at an angle to the blades, as in the. open position. Thus the movement together of the pressure plates in response to the pivotal action of the yoke and operating handle, respectively, in relation to the blades forces the blades to apply pressure against the jambs or terminals, and opposite rotation of the parts releases such contact pressure.

The cam followers 44 on the yoke 42 are aligned with the cam surfaces 32 of the terminals 18a and 18b, and have a similar curvature at their opposing ends 63, such ends having a small clearance from the cam surfaces 32 when the switch is in the fully closed position of FIG. 2, with a shoulder 64 of the operating handle abutting the base 12.

The opening of the switch is described as follows, having reference to FIGS. 1 and 2. An initial unclamping movement occurs as the operating handle 40 is pivoted counter clockwise as viewed in FIG. 2 through a fixed acute angle. The slot edge 48 bears on thepin 46, pivoting the yoke 42 clockwise about the axis of the bolt 54 until the cam follower surfaces 63 reach a position clear of the cam surfaces 32 of the terminals 18a and 18b. During this initial movement the pressure applied to the blades and terminals by the pressure plates 56 is released.

Further counter clockwise rotation of the operating arm 40, as viewed in FIG. 2, causes the blades 36 to pivot about the bolt 52 with the cam followers 44 in contact with the cam surfaces 30 of the terminals 18a and 18b, the parts ultimately reaching the fully open position. During this final phase of the opening movement the triangle linkage formed by the operating arm, the yoke and the blades is prevented from collapse, thus insuring that the pressure applying means remain unoperated.

The closing of the switch comprises two movements which are the reverse of the movements described above. The initial closing movement ends when the cam follower surfaces 63 of the yoke pass beyond the cam surfaces 30, thus putting the yoke 42 in position to pivot counter clockwise in relation to the blades, and when the bolt 54 has entered the slots 34 in the terminals 20a and 20b. The further clockwise rotation of the operating handle 40 during the second movement results in such counter clockwise rotation of the yoke 42 about the axis of the bolt 54, with the cam follower surfaces 63 guided by the cam surfaces 32 and the pressure plates 56 tightened together to apply pressure between the blades and terminals.

It will be observed that the current is split into two parallel paths, and two suitable arcing chambers of any desired type may be mounted over the jamb terminals 20a and 20b. These conventional arcing means are not shown in the drawing to avoid confusion with the operating parts herein described.

As will be evident from said Patent No. 2,960,590, the advantages of the pressure adjustment means herein described can be achieved with different embodiments. For example, instead of varying the pressure by rotating the bolts or shafts 52 and 54 within the pressure plates, other members may be pivotally mounted over the shafts and threaded into the pressure plates. In any case, the locking pins are securely held in place by the hair pin 62. Moreover, the hair pins can be easily removed when access is from thedirection as viewed in FIG. 1, which is commonly the most accessible direction.

It will be understood that various other modifications in the configuration of the parts and in their relative relationships, which will occur to those skilled in this art in connection with the different specific applications, may be provided without departing from the spirit or scope of this invention.

Having thus described the invention, I claim:

1. Pressure adjusting means for a bolted contact switch of the type having a pressure member passing through a blade and a jamb, comprising, in combination,

a pressure plate for threading on said pressure member and bearing on the blade, said plate having a peripheral groove defining flanges and also having a plurality of holes therethrough in communication with the groove,

a locking pin received in a selected pair of holes of the pressure plate and into a hole in the blade, and

means attached to the portion of the locking pin within the groove to retain it on the pressure plate.

2. The combination according to claim 1, in which the pressure member is a bolt threaded in the pressure plate.

3. The combination according to claim 1, in which the last-recited means comprises a pin received in a lateral hole in the locking pin.

4. The combination according to claim 1, in which the last-recited means comprises a looped pin received within a lateral hole in the locking pin and resiliently held in place therein.

References Cited UNITED STATES PATENTS 2,217,433 10/1940 Crabbs.

2,347,030 4/1944 Crabbs 200170 2,546,366 3/1951 Lindae 200-l 2,960,590 11/1960 Kussmaul et al.

3,180,963 4/1965 Hales et al. 200-470 3,183,335 5/1965 Cobbett.

3,255,322 6/1966 Ball et al. 200 3,410,974 11/1968 Kussmaul 200--162 H. O. JONES, Primary Examiner 

